Physiological Effects of Currents
初三颜色治疗的英语作文
初三颜色治疗的英语作文Color therapy, also known as chromotherapy, is an area of holistic healing that attributes therapeutic qualities to various colors and uses them to treat emotional and physical disturbances. The practice is rooted in the idea that colors create electrical impulses in our brains, which stimulate hormonal and biochemical processes in our body. These processes either calm or stimulate us.In junior high, students often experience a significant amount of stress due to academic pressures and the onset of adolescence. Color therapy can be introduced as a complementary treatment to help them cope with these challenges. For instance, the color blue has a profound calming effect and is often used to promote relaxation and peace. It can be particularly beneficial for students who suffer from anxiety or excessive stress.Green, the color of nature, is another soothing hue that is said to promote balance and harmony. It's believed to be beneficial for students who need to improve their concentration and calm their minds. Incorporating green into study spaces or using it during meditation can help create a tranquil environment conducive to learning.On the other hand, colors like red and orange are known for their energizing effects. Red is often associated with confidence and dynamism, which can be particularly useful for students who need a boost of energy or motivation. Orange, being a blend of red's passion and yellow's cheerfulness, is thought to encourage creativity and enthusiasm.Yellow, the brightest color perceived by the human eye, is synonymous with optimism and intellectual energy. It's suggested that this color can stimulate mental processes, encourage communication, and generate a sense of warmth and cheerfulness. For students who may feel demotivated or down, yellow can be a color to lift spirits and inspire a more positive outlook.Purple, a color often associated with spirituality and intuition, can also play a role in color therapy for students. It's believed to help foster creativity and imagination, which can be beneficial for subjects that require innovative thinking.The application of color therapy in a junior high setting can be as simple as painting the walls of classrooms in specific colors to elicit desired responses or using colored lights during certain activities. Teachers can also encourage students to wear or use stationery in colors that correspond to the type of activity they are engaging in, such as blue notebooks for writing assignments to promote calmness and focus.In conclusion, color therapy offers a non-invasive and creative approach to support the well-being of junior high students. By understanding the psychological and physiological effects of different colors, educators and parents can utilize this method to create a supportive and productive learning environment. As students navigate the complexities of their academic and personal lives, the strategic use of color can be a valuable tool in promoting a balanced and harmonious experience.。
医疗器械漏电流测试示意图
Safety Testing of Medical Electrical Equipment1 Hazards of Medical Electrical EquipmentMedical electrical equipment can present a range of hazards to the patient, the user, or to service personnel. Many such hazards are common to many or all types of medical electrical equipment, whilst others are peculiar to particular categories of equipment. Listed below are various types of common hazards.1.1 Mechanical HazardsAll types of medical electrical equipment can present mechanical hazards. These can range from insecure fittings of controls toloose fixings of wheels on equipment trolleys. The former may prevent a piece of life supporting equipment from being operated properly, whilst the latter could cause serious accidents in the clinical environment.Such hazards may seem too obvious to warrant mentioning, but it is unfortunately all too common for such mundane problems to be overlooked while more exotic problems are addressed.1.2 Risk of fire or explosionAll mains powered electrical equipment can present the risk of fire in the event of certain faults occurring such as internal or external short circuits. In certain environments such fires may cause explosions.Although the use of explosive anaesthetic gases is not common today, it should be recognised that many of the medical gases in use vigorously support combustion.1.3 Absence of FunctionSince many pieces of medical electrical equipment are life supporting or monitor vital functions, the absence of function of such a piece of equipment would not be merely inconvenient, but could threaten life.1.4 Excessive or insufficient outputIn order to perform its desired function equipment must deliver its specified output. Too high an output, for example, in the case ofsurgical diathermy units, would clearly be hazardous. Equally, too lowan output would result in inadequate therapy, which in turn may delay patient recovery, cause patient injury or even death. This highlights the importance of correct calibration procedures.1.5 InfectionMedical equipment that has been inadequately decontaminated afteruse may cause infection through the transmission of microorganismsto any person who subsequently comes into contact with it. Clearly, patients, nursing staff and service personnel are potentially atrisk here.1.6 MisuseMisuse of equipment is one of the most common causes of adverse incidents involving medical devices. Such misuse may be a result of inadequate user training or of poor user instructions.1.7 Risk of exposure to spurious electric currentsAll electrical equipment has the potential to expose people to therisk of spurious electric currents. In the case of medical electrical equipment, the risk is potentially greater since patients are intentionally connected to such equipment and may not benefit from the same natural protection factors that apply to people in other circumstances. Whilst all of the hazards listed are important, the prevention of many of them require methods peculiar to the particular type of equipment under consideration. For example, in order to avoid the risk of excessive output of surgical diathermy units, knowledge of radio frequency power measurement techniques is required. However, the electrical hazards are common to all types of medical electrical equipment and can minimised by the use of safety testing regimes which can be applied to all types of medical electrical equipment. For these reasons, it is the electrical hazards that are the main topic of this session.2 Physiological effects of electricity2.1 ElectrolysisThe movement of ions of opposite polarities in opposite directions through a medium is called electrolysis and can be made to occur bypassing DC current through body tissues or fluids. If a DC current is passed through body tissues for a period of minutes, ulceration begins to occur. Such ulcers, while not normally fatal, can bepainful and take long periods to heal.2.2 BurnsWhen an electric current passes through any substance havingelectrical resistance, heat is produced. The amount of heat depends on the power dissipated (I2R). Whether or not the heat produces a burn depends on the current density.Human tissue is capable of carrying electric current quite successfully. Skin normally has a fairly high electrical resistance while the moist tissue underneath the skin has a much lower resistance. Electrical burns often produce their most marked effects near to the skin, although it is fairly common for internalelectrical burns to be produced, which, if not fatal, can cause long lasting and painful injury.2.3 Muscle crampsWhen an electrical stimulus is applied to a motor nerve or a muscle, the muscle does exactly what it is designed to do in the presenceof such a stimulus i.e. it contracts. The prolonged involuntary contraction of muscles (tetanus) caused by an external electrical stimulus is responsible for the phenomenon where a person who is holding an electrically live object can be unable to let go.2.4 Respiratory arrestThe muscles between the ribs (intercostal muscles) need torepeatedly contract and relax in order to facilitate breathing. Prolonged tetanus of these muscles can therefore prevent breathing.2.5 Cardiac arrestThe heart is a muscular organ, which needs to be able to contract and relax repetitively in order to perform its function as a pump for the blood. Tetanus of the heart musculature will prevent the pumping process.2.6 Ventricular fibrillationThe ventricles of the heart are the chambers responsible for pumping blood out of the heart. When the heart is in ventricular fibrillation, the musculature of the ventricles undergoes irregular, uncoordinatedtwitching resulting in no net blood flow. The condition provesfatal if not corrected in a very short space of time.Ventricular fibrillation can be triggered by very small electrical stimuli. A current as low as 70 mA flowing from hand to hand acrossthe chest, or 20 μA directly through the heart may be sufficient. Itis for this reason that most deaths from electric shock areattributable to the occurrence of ventricular fibrillation.2.7 Effect of frequency on neuro-muscular stimulationThe amount of current required to stimulate muscles is dependent tosome extent on frequency. Referring to figure 1, it can be seen thatthe smallest current required to prevent the release of anelectrically live object occurs at a frequency of around 50 Hz.Above 10 kHz the neuro-muscular response to current decreases almost exponentially.Figure 1. Current required to prevent release of a live object.2.8 Natural protection factorsMany people have received electric shocks from mains potentials andabove and lived to tell the tale. Part of the reason for this is the existence of certain natural protection factors.Ordinarily, a person subject to an unexpected electrical stimulus is protected to some extent by automatic and intentional reflex actions.The automatic contraction of muscles on receiving an electricalstimulus often acts to disconnect the person from the source of the stimulus. Intentional reactions of the person receiving the shocknormally serve the same purpose. It is important to realise that apatient in the clinical environment who may have electrical equipmentintentionally connected to them and may also be anaesthetised are relatively unprotected by these mechanisms.Normally, a person who is subject to an electric shock receives the shock through the skin, which has a high electrical resistance compared to the moist body tissues below, and hence serves to reduce the amount of current that would otherwise flow. Again, a patient does not necessarily enjoy the same degree of protection. The resistance of the skin may intentionally have been lowered in order to allow good connections of monitoring electrodes to be made or, in the case of a patient undergoing surgery, there may be no skin present in the current path.The absence of natural protection factors as described above highlights the need for stringent electrical safetyspecifications for medical electrical equipment and for routinetest and inspection regimes aimed at verifying electrical safety.3 Leakage currents3.1 Causes of leakage currentsIf any conductor is raised to a potential above that of earth, some current is bound to flow from that conductor to earth. This is true even of conductors that are well insulated from earth, since there is no such thing as perfect insulation or infinite impedance. The amount of current that flows depends on:a.the voltage on the conductor.b.the capacitive reactance between the conductor and earth.c.the resistance between the conductor and earth.The currents that flow from or between conductors that are insulated from earth and from each other are called leakage currents, and are normally small. However, since the amount of current required to produce adverse physiological effects is also small, such currents must be limited by the design of equipment to safe values.For medical electrical equipment, several different leakagecurrents are defined according to the paths that the currents take.3.2 Earth leakage currentEarth leakage current is the current that normally flows in the earth conductor of a protectively earthed piece of equipment. In medical electrical equipment, very often, the mains is connected to a transformer having an earthed screen. Most of the earth leakage current finds its way to earth via the impedance of the insulation between the transformer primary and the inter-winding screen, since this is the point at which the insulation impedance is at its lowest (see figure 2).Figure 2. Earth leakage current path.Under normal conditions, a person who is in contact with the earthed metal enclosure of the equipment and with another earthed object would suffer no adverse effects even if a fairly large earth leakage current were to flow. This is because the impedance to earth from the enclosure is much lower through the protective earth conductor than it is through the person. However, if the protective earth conductor becomes open circuited, then the situation changes. Now, if the impedance between the transformer primary and the enclosure is of the same order of magnitude as the impedance between the enclosure and earth through the person, then a shock hazard exists.It is a fundamental safety requirement that in the event of a single fault occurring, such as the earth becoming open circuit, no hazard should exist. It is clear that in order for this to be the case in the above example, the impedance between the transformer primary and the enclosure needs to be high. This would be evidenced when theequipment is in the normal condition by a low earth leakage current. In other words, if the earth leakage current is low then the riskof electric shock in the event of a fault is reduced.3.3 Enclosure leakage currentEnclosure leakage current is defined as the current that flows from an exposed conductive part of the enclosure to earth through a conductor other than the protective earth conductor. However, if a protective earth conductor is connected to the enclosure, there is little point in attempting to measure the enclosure leakage current from another protectively earthed point on the enclosure since any measuring device used is effectively shorted out by the low resistance of the protective earth. Equally, there is little point in measuring the enclosure leakage current from a protectively earthed point on the enclosure with the protective earth open circuit, since this would give the same reading as measurement of earth leakage current as described above. For these reasons, it is usual when testing medical electrical equipment to measure enclosure leakage current from points on the enclosure that are not intended to be protectively earthed (see figure 3). On many pieces of equipment, no such points exist. This is not a problem. The test is included intest regimes to cover the eventuality where such points do exist and to ensure that no hazardous leakage currents will flow from them.Figure 3. Enclosure leakage current path.3.4 Patient leakage currentPatient leakage current is the leakage current that flows through a patient connected to an applied part or parts. It can either flow from the applied parts via the patient to earth or from an external source of high potential via the patient and the applied parts to earth. Figures 4a and 4b illustrate the two scenarios.Figure 4a. Patient leakage current path from equipment.Figure 4b. Patient leakage current path to equipment.3.5 Patient auxiliary currentThe patient auxiliary current is defined as the current that normally flows between parts of the applied part through the patient, which is not intended to produce a physiological effect (see figure 5).Figure 5. Patient auxiliary current path.6 Electrical Safety Tests6.1 Normal condition and single fault conditionsA basic principle behind the philosophy of electrical safety isthat in the event of a single abnormal external condition arisingor of the failure of a single means of protection against a hazard, no safety hazard should arise. Such conditions are called "single fault conditions" (SFC's) and include such situations as the interruption of the protective earth conductor or of one supply conductor, the appearance of an external voltage on an applied part, the failure of basic insulation or of temperature limiting devices.Where a single fault condition is not applied, the equipment is said to be in "normal condition" (NC). However, it is important to understand that in this condition, the performance of certain tests may compromise the means of protection against electric shock. For example, if earth leakage current is measured in normal condition, the impedance of the measuring device in series with the protective earth conductor means that there is no effective supplementary protection against electric shock.Many electrical safety tests are carried out under single fault conditions since these represent the worst case and will give the most adverse results. Clearly the safety of the equipment under test may be compromised when such tests are performed. Personnel carrying out electrical safety tests should be aware that the normal means for protection against electric shock are not necessarily operative during testing and should therefore exercise due precautions fortheir own safety and that of others.6.2 Protective Earth ContinuityThe resistance of the protective earth conductor is measured between the earth pin on the mains plug and a protectively earthed point on the equipment enclosure (see figure 6). The reading should not normally exceed 0.2 O at any such point. The test is obviously only applicable to class I equipment.In IEC60601, the test is conducted using a 50Hz current between 10A and 25A for a period of at least 5 seconds. Although this is a type test, some medical equipment safety testers mimic this method. Damage to equipment can occur if high currents are passed to points that are not protectively earthed, for example, functional earths. Great care should be taken when high current testers are used to ensure that the probe is connected to a point that is intended to be protectively earthed.HEI 95 and DB9801 Supplement 1 recommend that the test be carried out at a current of 1A or less for the reason described above. Where the instrument used does not do so automatically, the resistance of the test leads used should be deducted from the reading.If protective earth continuity is satisfactory then insulationtests can be performed.Applicable to Class I, all typesLimit: 0.2DB9801 Yes, at 1A orless.recommended?:HEI 95 recommended?: Yes, at 1A or less.Ensure probe is on a protectively earthedNotes:pointFigure 8. Measurement of protective earth continuity.6.3 Insulation TestsIEC 60601-1, clause 17, lays down specifications for electricalseparation of parts of medical electrical equipment compliance towhich is essentially verified by inspection and measurement ofleakage currents. Further tests on insulation are detailed underclause 20, "dielectric strength". These tests use AC sources to testequipment that has been pre-conditioned to specified levels ofhumidity. The tests described in the standard are type tests and arenot suitable for use as routine tests.HEI 95 and DB9801 recommend that for class I equipment theinsulation resistance is measured at the mains plug between the liveand neutral pins connected together and the earth pin. Whereas HEI95 recommends using a 500V DC insulation tester, DB 9801 recommendsthe use of 350V DC as the test voltage. In practice this lastrequirement could prove difficult and it is acknowledged in afootnote that a 500 V DC test voltage is unlikely to cause any harm.The value obtained should normally be in excess of 50M Ω but may be less in exceptional circumstances. For example, equipment containingmineral insulated heaters may have an insulation resistance as low as1MΩ with no fault present. The test should be conducted with allfuses intact and equipment switched on (see figure 9).Applicable to Class I, all typesLimits: Not less than 50M ΩDB9801Yesrecommended?:HEI 95Yesrecommended?:Equipment containing mineral insulated heatersNotes: may give values down to 1M Ω . Check equipmentis switched on.Figure 9. Measurement of insulation resistance for class I equipmentHEI 95 further recommends for class II equipment that the insulationresistance be measured between all applied parts connected togetherand any accessible conductive parts of the equipment. The valueshould not normally be less than 50M Ω (see figure 10). DB9801 Supplement 1 does not recommend any form of insulation test beapplied to class II equipment.Applicable to Class II, all types having applied parts Limits: not less than 50M Ω.DB9801 recommended?: NoHEI 95 recommended?: YesNotes: Move probe to find worst case.Figure 10. Measurement of insulation resistance for class II equipment.Satisfactory earth continuity and insulation test results indicatethat it is safe to proceed to leakage current tests.6.4 Leakage current measuring deviceThe leakage current measuring device recommended by IEC 60601-1 loadsthe leakage current source with a resistive impedance of about 1 kOand has a half power point at about 1kHz. The recommended measuringdevice was changed slightly in detail between the 1979 and 1989version but remained functionally very similar. Figure 11 showssuitable arrangements for the measuring device. The millivolt meterused should be true RMS reading and should have an inputimpedance greater than 1 M Ω . In practice this is easily achievable with most good quality modern multimeters. The meter in thearrangements shown measures 1mV for each Aμof leakage current.Figure 11. Suitable arrangements for measurement of leakage currents.6.5 Earth Leakage CurrentFor class I equipment, earth leakage current is measured as shown infigure 12. The current should be measured with the mains polaritynormal and reversed. HEI 95 and DB9801 Supplement 1 recommend thatthe earth leakage current be measured in normal condition (NC) only.Many safety testers offer the opportunity to perform the test under asingle fault condition such as live or neutral conductor open circuit.Applicable to Class I equipment, all types0.5mA in NC, 1mA in SFC or 5mA and 10mA Limits: respectively for permanently installedequipment.DB9801Yes, in normal condition only. recommended?:HEI 95Yes, in normal condition only. recommended?:Measure with mains normal and reversed. Notes:Ensure equipment is switched on.Figure 12. Measurement of Earth Leakage Current.6.6 Enclosure leakage currentEnclosure leakage current is measured between an exposed part of the equipment which is not intended to be protectively earthed and true earth as shown in figure 13. The test is applicable to both class I and class II equipment and should be performed with mains polarity both normal and reversed. HEI 95 recommends that the test be performed under the SFC protective earth open circuit for class I equipment and under normal condition for class II equipment. DB9801 Supplement 1 recommends that the test be carried out under normal condition onlyfor both class I and class II equipment. Many safety testers also allow the SFC's of interruption of live or neutral conductors to be selected. Points on class I equipment which are likely not to be protectively earthed may include front panel fascias, handle assemblies etc.Applicable to Class I and class II equipment, all types. Limits: 0.1mA in NC, 0.5mA in SFCDB9801Yes, NC onlyrecommended?:HEI 95 Yes, class I SFC earth open circuit, class IINC.recommended?:Ensure equipment switched on. Normal and Notes:reverse mains. Move probe to find worst case.Figure 13. Measurement of Enclosure Leakage Current.6.7 Patient leakage currentUnder IEC 60601-1 and HEI 95, for class I and class II type B and BF equipment, the patient leakage current is measured from all applied parts having the same function connected together and true earth (figure 14). For type CF equipment the current is measured from each applied part in turn and the leakage current leakage must not be exceeded at any one applied part (figure 15).DB9801 Supplement 1 recommends that patient leakage current be measured from each applied part in turn for all types of equipment, although the recommended leakage current limits have not beenrevised to take into account the changed test method for B and BF equipment.Great care must be taken when performing patient leakage current measurements that equipment outputs are inactive. In particular,outputs of diathermy equipment and stimulators can be fatal and can damage test equipment.Applicable toAll classes, type B & BF equipment havingapplied parts.Limits: 0.1mA in NC, 0.5mA in SFC.DB9801Norecommended?:HEI 95 Yes, class I SFC earth open circuit, class IIrecommended?: normal condition.Notes:Equipment on but outputs inactive. Normaland reverse mains.Figure 14. Measurement of Patient Leakage Current with applied parts connectedApplicable totogether.Class I and class II, type CF (B & BF for DB9801 only) equipment having applied parts.Limits: 0.01mA in NC, 0.05mA in SFC.DB9801Yes, all types, normal condition only. recommended?:HEI 95 Yes, type CF only, class I SFC earth open circuit,recommended?: class II normal condition.Notes:Equipment on but outputs inactive. Normal andreverse mains. Limits are per electrode.Figure 15. Measurement of patient leakage current for each applied part in turn6.8 Patient auxiliary currentPatient auxiliary current as defined in section 3.5 is measuredbetween any single patient connection and all other patientconnections of the same module connected together. It is not usual totest all possible combinations since together with all possiblesingle fault conditions this would give an exceedingly large amountof data of questionable value.All classes and types of equipment havingApplicable toapplied parts.Type B & BF - 0.1mA in NC, 0.5mA in SFC.Limits:Type CF - 0.01mA in NC, 0.05mA in SFC.DB9801No.recommended?:HEI 95No.recommended?:Ensure outputs are inactive. Normal andNotes:reverse mains.Figure 16. Measurement of patient auxiliary current.6.9 Mains on applied partsBy applying mains voltage to the applied parts, the leakage currentthat would flow from an external source into the patient circuitscan be measured. The measuring arrangement is illustrated in figure18.Although the safety tester normally places a current limitingresistor in series with the measuring device for the performance ofthis test, a shock hazard still exists. Therefore, great care shouldbe taken if the test is carried out in order to avoid the hazard presented by applying mains voltage to the applied parts.Careful consideration should be given as to the necessity orusefulness of performing this test on a routine basis when weighedagainst the associated hazard and the possibility of causing problemswith equipment. The purpose of the test under IEC 60601-1 is toensure that there is no danger of electric shock to a patient who for some unspecified reason is raised to a potential above earth due tothe connection of the applied parts of the equipment under test. The standard requires that the leakage current limits specified are not exceeded. There is no guarantee that equipment performance will notbe adversely affected by the performance of the test. In particular, caution should be exercised in the case of sensitive physiological measurement equipment. In short, the test is a "type test".Class I & class II, types BF & CF having applied Applicable toparts.Limit: Type BF - 5mA; type CF - 0.05mA per electrode.DB9801No.recommended?:HEI 95 Norecommended?:Ensure outputs are inactive. Normal and reverse Notes: mains. Caution required, especially onphysiological measurement equipment.Figure 17. Mains on applied parts measurement arrangement.6.10 Leakage current summaryThe following table summarises the leakage current limits (in mA)specified by IEC60601-1 for the tests most commonly performed asroutine tests. Limits for DB9801 recommended tests are underlined.Limits for HEI 95 recommended tests are given in bold type.Type B Type BF Type CF Leakage currentNC SFC NC SFC NC SFC Earth 0.5 1 0.5 1 0.5 1Earth for fixed5 10 5 10 5 10 equipmentEnclosure 0.1 0.5 0.1 0.5 0.1 0.5 Patient 0.1 0.5 0.1 0.5 0.01 0.05Mains on applied- - - 5 - 0.05 partPatient auxiliary 0.1 0.5 0.1 0.5 0.01 0.05*For class II type CF equipment HEI95 recommends a limit forenclosure leakage current of 0.01mA as per the 1979 edition of BS5724.Table 2. Leakage current limits summary.6.11 Comparison of HEI 95 and DB 9801 Supplement 1recommendationsTest HEI 95Use test current of 1A Earth continuity or lessLimit 0.2ohmMeasure between Land N connected Insulation for Class 1together and E using500v DC tester. equipmentLimit > 50M Ω .Investigate lowervaluesMeasure betweenapplied parts andaccessible conductive Insulation for Class II parts of theequipment equipment.Limit > 50M Ω .Investigate lowervaluesMeasure in normalEarth leakage current conditionLimit < 0.5mAMeasure in SFC, earthopen circuitforEnclosure leakageClass-1, NC forClass-IIcurrentLimit <0.5 mA forClass1<0.1 mA for class IIMeasure from allapplied partsconnected together forB & BF equipment andPatient leakage from each applied part in turn for type CF.current Measure under SFC,eart open circuit forClass 1, NC for classII.Limits :Class I, B& BF <DB9801Supplement 1Use test current of 1A or lessLimit 0.2ohmMeasure between L and N connected together and E using 350v DC tester. Limit > 20M Ω . Investigate lower valuesNo recommendation.Measure in normalconditionLimit < 0.5mAMeasure in NC onlyLimit < 0.1 mAMeasure from eachapplied part in turn,for all types ofequipmentMeasure under NConlyLimitsType B & BF<0.1 mA perelectrodeType CF < 0.01。
药学英语_2020春《药学英语》期末考试0
答案:
6.单项选择题： It was discovered centuries ago that preparations could be made from certain plants，such as poppies and coca，which，when taken by a human being，serve to deaden pain(are " analgesics ")．
试卷总分:100 得分:45
1.单项选择题： If you eat enough cereals，peas，beans，eggs and tomatoes，you get a good supply of vitamin B 1 ．This keeps your nerves in good condition and helps appetite and " digestion "．
A.处方药
B.非处方药
C.中药
D.西药
答案:
12.单项选择题： " Reserpine " and vincaleukoblastine represent the most important plant-derived medicinals introduced into medicine by our generation．
A.慢性的
B.急性的
C.恶性的
D.良性的
答案:
22.单项选择题： Vincaleukoblastine and Vincristine from Vinca rosea are now among the most important drugs for the treatment of acute " leukemia " of childhood and other neoplasms．
2023届湖北省武汉市高三五月模拟训练英语试题(4)
1. Which tour does the man seem to be interested in?A．The evening tour.B．The half-day tour.C．The full-day tour.2.A．The boss treats Johnson in an unfair manner.B．Johnson is not willing to work far from home.C．Johnson is not intelligent enough to be promoted.D．The boss puts cooperation first while giving promotions.3.A．The electronic toy is unique.B．The toy is safe for all users.C．Plastic toys are of low quality.D．The toy isn’t environmentally friendly.4. Where does the conversation most probably take place?A．At school.B．In a post office.C．At a clothing store.5. What’s the matter with Laura?A．She is under work pressure.B．She pressed the wrong button.C．She broke the printing machine.二、听力选择题6. 听下面一段较长对话，回答以下小题。
1. What will Finn do this weekend?A．Go to the theatre.B．Travel with his parents.C．Train for a football match.2. When was Teatre Sans built?A．In the 14th century.B．In the 19th century.C．In the 20th century.3. What did Teatre Sans serve as originally?A．A marketplace.B．A company’s headquarters.C．A place for political meetings.7. 听下面一段较长对话，回答以下小题。
英语阅读理解题20套(带答案)及解析
英语阅读理解题20套（带答案）及解析一、阅读理解题及答案1. 阅读材料：问题：Why do Tom's parents worry about him?答案：A. They think he spends too much time on sports.2. 阅读材料：Lucy is a primary school teacher. She is very patient and always encourages her students to be confident. Many students like her because she makes learning fun.问题：What is Lucy's occupation?答案：B. Teacher二、解析1. 第一题解析：本题考查学生对文章细节的理解。
从阅读材料中可以看出，Tom的父母担心他因为过于沉迷篮球而忽视学业。
因此，正确答案为A。
2. 第二题解析：本题考查学生对文章主要人物职业的把握。
文章明确提到Lucy是一名小学老师，因此正确答案为B。
三、提高阅读理解能力的技巧1. 先读题目，再读文章。
这样可以在阅读时更有针对性地寻找答案。
2. 注意文章的和副，它们往往揭示了文章的主旨。
3. 留意文章中的关键词和主题句，这些往往是理解文章大意的关键。
4. 学会略读和扫读，快速获取文章大意，然后再进行细读寻找具体信息。
5. 遇到生词时，不要慌张，可以根据上下文推测词义。
四、实例解析阅读材料：问题：What is the purpose of the "Greening Greenfield" project?答案：C. To make the town more environmentally friendly and improve the quality of life.解析：本题考查学生对文章主旨的理解。
剑桥雅思6Test3Passage3原文+解析
雅思为各位考生推荐复习材料-剑桥雅思6Test3Passage3原文+解析,需要延伸拓展本单元其他篇幅的同学，请点击：剑桥雅思6test2passage3阅读原文+题目+答案解析。
剑桥雅思6Test3Passage3原文You should spend about 20 minutes on Questions 28-40, which are based on Reading Passage 3 below.The Search for the Anti-aging PillIn government laboratories and elsewhere, scientists are seeking a drug able to prolong life and youthful vigor. Studies of caloric restriction are showing the wayAs researchers on aging noted recently, no treatment on the market today has been proved to slow human aging — the build-up of molecular and cellular damage that increases vulnerability to infirmity as we grow older. But one intervention, consumption of a low-calorie*yet nutritionally balanced diet, works incredibly well in a broad range of animals, increasing longevity and prolonging good health. Those findings suggest that caloric restriction could delay aging and increase longevity in humans, too.Unfortunately, for maximum benefit, people would probably have to reduce their caloric intake by roughly thirty per cent, equivalent to dropping from 2,500 calories a day to 1,750. Few mortals could stick to that harsh a regimen, especially for years on end. But what if someone could create a pill that mimicked the physiological effects of eating less without actually forcing people to eat less? Could such a ‘caloric-restriction mimetic’, as we call it, enable people to stay healthy longer, postponing age-related disorders (such as diabetes, arteriosclerosis, heart disease and cancer) until very late in life? Scientists first posed this question in the mid-1990s, after researchers came upon a chemical agent that in rodents seemed to reproduce many of caloric restriction’s benefits. No compound that would safely achieve the same feat in people has been found yet, but the search has been informative and has fanned hope that caloric-restriction (CR) mimetics can indeed be developed eventually.The benefits of caloric restrictionThe hunt for CR mimetics grew out of a desire to better understand caloric restriction’s many effects on the body. Scientists first recognized the value of the practice more than 60 years ago, when they found that rats fed a low-calorie diet lived longer on average than free-feeding rats and also had a reduced incidence of conditions that become increasingly common in old age. What is more, some of the treated animals survived longer than the oldest-living animals in the control group, which means that the maximum lifespan (the oldest attainable age), not merely the normal lifespan, increased. Various interventions, such as infection-fighting drugs, can increase a population’s average survival time, but only approaches that slow the body’s rate of aging will increase the maximum lifespan.The rat findings have been replicated many times and extended to creatures ranging from yeast to fruit flies, worms, fish, spiders, mice and hamsters. Until fairly recently, the studies were limited to short-lived creatures genetically distant from humans. But caloric-restriction projects underway in two species more closely related to humans — rhesus and squirrel monkeys — have made scientists optimistic that CR mimetics could help people.calorie: a measure of the energy value of foodThe monkey projects demonstrate that, compared with control animals that eat normally, caloric-restricted monkeys have lower body temperatures and levels of the pancreatic hormone insulin, and they retain more youthful levels of certain hormones that tend to fall with age.The caloric-restricted animals also look better on indicators of risk for age-related diseases. For example, they have lower blood pressure and triglyceride levels (signifying a decreased likelihood of heart disease), and they have more normal blood glucose levels (pointing to a reduced risk for diabetes, which is marked by unusually high blood glucose levels). Further, it has recently been shown that rhesus monkeys kept on caloric-restricted diets for an extended time (nearly 15 years) have less chronic disease. They and the other monkeys must be followed still longer, however, to know whether low-calorie intake can increase both average and maximum life spans in monkeys. Unlike the multitude of elixirs being touted as the latest anti-aging cure, CR mimetics would alter fundamental processes that underlie aging. We aim to develop compounds that fool cells into activating maintenance and repair.How a prototype caloric-restriction mimetic worksThe best-studied candidate for a caloric-restriction mimetic, 2DG (2-deoxy-D-glucose), works by interfering with the way cells process glucose. It has proved toxic at some doses in animals and so cannot be used in humans. But it has demonstrated that chemicals can replicate the effects of caloric restriction; the trick is finding the right one.Cells use the glucose from food to generate ATP (adenosine triphosphate), the molecule that powers many activities in the body. By limiting food intake, caloric restriction minimizes the amount of glucose entering cells and decreases ATP generation. When 2DG is administered to animals that eat normally, glucose reaches cells in abundance but the drug prevents most of it from being processed and thus reduces ATP synthesis. Researchers have proposed several explanations for why interruption of glucose processing and ATP production might retard aging. One possibility relates to the ATP-making machinery’s emission of free radicals, which are thought to contribute to aging and to such age-related diseases as cancer by damaging cells. Reduced operation of the machinery should limit their production and thereby constrain the damage. Another hypothesis suggests that decreased processing of glucose could indicate to cells that food is scarce (even if it isn’t) and induce them to shift into an anti-aging mode。
福建省2024届高中毕业班适应性练习英语试卷(含答案)
福建省2024届高中毕业班适应性练习英语试卷学校：___________姓名：___________班级：___________考号：___________一、听力题1．Where does the conversation probably take place?A. In a library.B. In a supermarket.C. In a restaurant2．What sport do the speakers both like?A. Running.B. Swimming.C. Hiking.3．What are the speakers talking about?A. Pocket money.B. The value of money.C. Money saving.4．What is David busy doing?A. Visiting a flatB. Introducing a flat.C. Arranging a flat5．How much will the man pay for the magazines?A. $50.B. $80.C. $100.听一段材料, 回答以下小题。
6．How many multiple-choices remain unfinished?A. 3.B. 4.C. 7.7．How did Linda perform in the free response questions?A. Fairly well.B. Just so-so.C. Quite badly.听一段材料, 回答以下小题。
8．What do we know about Venice at the beginning of March?A. It has a travel off-season.B. It has a wonderful concert.C. It has a traditional celebration.9．Why are the speakers going to make up?A. To show love for Venetians.B. To adapt to the local custom.C. To make themselves elegant.10．What is the probable relationship between the speakers?A. Husband and wife.C. Director and actor.听一段材料, 回答以下小题。
2023年北京重点校高三(上)期末英语汇编：阅读理解C篇
2023年北京重点校高三（上）期末英语汇编阅读理解C篇一、阅读理解（2023秋·北京顺义·高三统考期末）For astronomers who are sighted, the Universe is full of visual wonders. From shimmering planets to shinning galaxies(星系), the universe is impressively beautiful. But those who are visually impaired cannot share that experience. So astronomers have been developing alternative ways to convey(传递)scientific information.Recently, the journal Nature Astronomy published the latest in a series of articles on the use of sonification in astronomy. Sonification describes the change of data into digital audio(声音)files, which allows them to be heard, as well as read and seen.In August, Kimberly Arcand, a data-visualization expert and science communicator at the Center for Astrophysics and others transformed some of the first images of the black hole at the centre of the Perseus cluster from the James Webb Space Telescope into sound. They worked under the guidance of people who are blind to map the intensity and colours of light in the headline-grabbing pictures into audio. The sonification of an image of gas and dust in a distant nebula(星云), for instance, uses loud high-frequency sounds to represent bright light near the top of the image, but lower-frequency loud sounds to represent bright light near the image’s centre. The black hole sonification translates data on sound waves travelling through space-created by the black hole’s impact on the hot gas that surrounds it-into the range of human hearing.Scientists in other fields have also experimented with data sonification. Some have explored whether it can help with discovering Alzheimer’s disease from brain scans. Sound has even been used to describe ecological shifts caused by climate change in an Alaskan forest, with researchers assigning various musical instruments to different tree species.In the long run, such approaches need to be strictly evaluated to determine what they can offer that other techniques cannot. For all the technical accuracy displayed in individual projects, the Nature Astronomy series points out that there are no universally accepted standards for sonifying scientific data, and little published work that evaluates its effectiveness.1．What does the underlined word “impaired” in Paragraph 1 most probably mean?A．Appealing. B．Damaged. C．Directed. D．Impressive.2．The examples in Paragraph 4 are intended to ______.A．show the widespread use of sonificationB．introduce the common process of sonificationC．provide people with the cure for particular diseasesD．improve the application of sonification to more fields3．As for sonification, which would the author agree with?A．The use of sonification helps to analyze data effectively.B．The standardization of sonification has yet to be achieved.C．Sonification can transform some data that other techniques cannot.D．Lower-frequency sounds show bright light near the top of the image.（2023秋·北京朝阳·高三统考期末）Finland was known as a rather quiet country. Since 2008, the Country Brand Delegation (国家品牌代表团) has been looking for a national brand that would make some noise to market the country as a world-famous tourist destination. In 2010, the Delegation issued a “Country Brand Report,” which highlighted a host of marketable themes, including Finland’s famous educational system. One key theme was brand new: silence. As the report explained, modern society often seems intolerably loud and busy. “Silence is a resource,” it said.Silence first appeared in scientific research as a control or baseline, against which scientists compare the effects of noise or music. Researchers have mainly studied it by accident, as physician Luciano Bernardi did in his study of the physiological (生理学) effects of music. “We didn’t think about the effect of silence,” he said. Bernardi observed two dozen test subjects while they listened to six musical tracks. He found that the impacts of music could be read directly in the bloodstream, via changes in blood pressure, carbon dioxide, and circulation in the brain. “During almost all sorts of music, there was a physiological change with a condition of arousal (兴奋),” he explained.This effect made sense, given that active listening requires attention. But the more striking finding appeared between musical tracks. Bernardi and his colleagues discovered that randomly added stretches of silence also had a great effect, but in the opposite direction. In fact, two-minute silent pauses proved far more relaxing than either “relaxing” music or a longer silence played before the experiment started. The blank pauses that Bernardi had considered irrelevant, in other words, became the most interesting object of study. Silence seemed to be heightened by contrasts, maybe because it gave test subjects a release from careful attention. “Perhaps the arousal is something that concentrates the mind in one direction, so that when there is nothing more arousing, then you have deeper relaxation,” he said.This finding is reinforced by neurological (神经系统的) research. Relevant research shows when our brains rest quietly, they integrate external and internal information into “a conscious (意识的) workspace.” Freedom from noise and goal-directed tasks, it appears, unites the quiet without and within, allowing our conscious workspace to do its thing to discover where we fit in.Noora Vikman, a consultant on silence for Finland’s marketers, knows silence well. Living in a remote and quiet place in Finland, she discovers thoughts and feelings that aren’t detectable in her busy daily life. “If you want to know yourself, you have to be with yourself, and discuss with yourself, and be able to talk with yourself.” 4．Why does the author mention the Country Brand Report in Paragraph 1?A．To present how Finland viewed silence.B．To highlight the need of noise in Finland.C．To explain why Finland issued the brands.D．To indicate the authority of the Delegation.5．What can be inferred about Luciano Bernardi’s discovery?A．It challenged the calming effect of music.B．It emphasized the role of silence between sounds.C．It illustrated the loss of attentiveness after silence.D．It stated brains’ information processing in the quiet.6．As for Noora Vikman’s attitude to silence, the author is ________.A．doubtful B．supportive C．disapproving D．unconcerned7．Which would be the best title for the passage?A．Silence: A Limited Resource B．Silence: A Misunderstood ToolC．Silence: The Unexpected Power D．Silence: The Value by Contrasts（2023秋·北京通州·高三统考期末）NASA’s spacecraft Dart hit an asteroid (小行星) 11.3 million kilometers away at a speed, changing the asteroid’s orbit and lowered its cycle period by I5 minutes, the space organization announced on Monday.Some said the move shows the world might now be able to prevent asteroids — the kind that made the dinosaurs extinct — from hitting the Earth. The asteroid that was controlled belonged to a double-asteroid system. It had a 160-meter diameter while the other asteroid’s diameter is over 500 meters. The bigger asteroid can be compared to the one that ended the dinosaur era 67 million years ago. A hit from an asteroid that size can cause unimaginable destruction.However, it is too early to assert that the world has gained the ability to prevent asteroids from hitting us. The asteroid that was controlled was only 160 meters in size. Its cycle period was changed, without changing its orbit significantly. It is still not clear if the orbit of a much larger asteroid headed toward the Earth can be changed successfully.In brief, NASA’s success in changing the course of a harmful asteroid is definitely praiseworthy, but much more needs to be done before we can say the world’s security from some unpredictable asteroid is guaranteed.It should be noted that changing the orbit of an asteroid involves more than just sending an object into space and commanding it to hit the asteroid. While it is hard enough to hit an asteroid, it is even more difficult to lock onto one in the first place. It means having the ability to observe approaching asteroids, measuring their respective speeds, and deciding which ones might pose a danger to the Earth.Therefore, there’s more to Dart hitting the asteroid than meets the eye. And these are key areas where global scientists need to work harder in the future.8．What was the latest news about NASA?A．Its new program failed.B．Its manned spaceship hit an asteroid.C．Its spacecraft changed an asteroid’s orbit.D．Its spacecraft saved the earth from being destroyed.9．What does the underlined word “assert” in Paragraph 3 most probably mean?A．Advise. B．State. C．Promise. D．Admit.10．What can we learn about the asteroid that was hit?A．It was comparatively small in size.B．Its orbit was changed significantly.C．It travelled at a higher speed than before.D．It was powerful enough to end dinosaur era.11．What is the author’s attitude toward using spacecrafts to change the asteroids orbits?A．Neutral. B．Optimistic.C．Pessimistic. D．Not mentioned.（2023秋·北京房山·高三统考期末）With the development of technology, “paperless” seems to be the new trend. Instead of writing by hand, people began to use computers to type in order to produce text quickly. Some people said word processing made producing and editing text much easier. Will handwriting be completely replaced by typing?A 2017 study in the journal Frontiers in Psychology found that regions of the brain associated with learning were more active when subjects completed a task by hand instead of on a keyboard. Not only that, but the study’s authors also found that writing by hand could promote “deep encoding or processing” in a way that typing does not.In fact, there have been many such studies to arrive at that conclusion. One notable example from 2014 compared students who took notes by hand with those who took notes on laptops. They found that the students using laptops tended to write down what the professor said word for word, while those who took notes by hand were more likely to listen to what was being said, analyzing it for important content and “processing information and reframing it in their own words.” When asked conceptual questions about the lecture, students who had taken notes by hand were better able to answer than those who had typed their notes.Daniel Oppenheimer, one of the study’s co-authors, told Medium’s Elemental that in order to analyze the lecture, people had to contemplate the material and actually understand the arguments. This helped them learn the material better. The most annoying thing about writing by hand is also what makes it so effective for learning.Virginia Berninger, a professor at the University of Washington, says, “When we write a letter of the alphabet, the process of production involves pathways in the brain that go near or through parts that manage emotion.” Pressing a key doesn’t stimulate those pathways the same way. She says, “It’s possible that there’s not the same connection to the emotional part of the brain when people type, as opposed to writing in longhand.” “In the same vein, writing in longhand also allows people to really figure out what they mean to say,” Oppenheimer says, “which may help self-expression.”Our keyboards are great for a lot of things. But sometimes, there’s no replacing the feeling of spreading out a clean sheet of paper, uncapping a beloved pen, and letting the ink flow.12．The author uses the question underlined in Paragraph 1 to ________.A．predict the ending B．introduce the topicC．emphasize an opinion D．draw a conclusion13．What can be inferred from the passage?A．People who write by hand tend to think deeply.B．People who write by hand are likely to make comparisons.C．People who write by hand slow down their learning process.D．People who write by hand find it difficult to improve their memory.14．As for handwriting, the author thinks it is ________.A．accurate B．unimportant C．annoying D．beneficial（2023秋·北京丰台·高三统考期末）Over millions of years humans have responded to certain situationswithout thinking too hard. If our ancestors spotted movement in the nearby forest, they would run first and question later. At the same time, the ability to analyze and to plan is part of what separates us from other animals. The question of when to trust your instinct (直觉)and when to think slow matters in the office as much as in the savannah(草原).Slow thinking is the feature of a well-managed workplace. Yet instinct also has its place. Some decisions are more connected to emotional responses and less to analysis. In demanding customer-service or public-facing situations, instinct is often a better guide to how to behave.Instinct can also be improved. Plenty of research has shown that instinct becomes more unerring with experience. In one well-known experiment, volunteers were asked to assess whether a selection of designer handbags were real or not. Some were instructed to operate on instinct and others to deliberate(深思熟虑)over their decision. Instinct worked better for those who owned at least three designer handbags; indeed, it outperformed analysis. The more expert you become, the better your instinct tends to be.However, the real reason to embrace fast thinking is that it is, well, fast. It is often the only way to get through the day. To take one example, when your inbox floods with new emails at the start of a new day, there is absolutely no way to read them all carefully. Instinct is what helps you decide which ones to answer and which to delete or leave unopened. Fast thinking can also help the entire organization. The value of many managerial decisions lies in the simple fact that they have been made at all. Yet as data explodes, the temptation(诱惑)to ask for one more bit of analysis has become much harder to resist. Managers often suffer from overthinking, turning a simple problem into a complex one.When to use instinct in the workplace rests on its own form of pattern recognition. Does the decision maker have real expertise in this area? Is this a field in which emotion matters more than reasoning? Above all, is it worth delaying the decision? Slow thinking is needed to get the big calls right. But fast thinking is the way to stop deliberation turning to a waste of time.15．What does the underlined word “unerring” in Paragraph 3 probably mean?A．Accurate. B．Creative. C．Controllable. D．Obvious.16．What can we learn from the passage?A．Managers can afford the cost of slow thinking.B．Fast thinking can be a boost to work efficiency.C．Slow thinking will hold us back in the long run.D．Too much data is to blame for wrong decisions.17．What is the author's purpose of writing the passage?A．To explain how instinct works.B．To compare instinct and slow thinking.C．To highlight the value of instinct in the workplace.D．To illustrate the development of different thinking patterns.（2023秋·北京海淀·高三统考期末）A new study has found human feelings can accurately be expressed numerically and have more predictive power for how we behave than formal studies of socioeconomic factors like household income and employment status.The study co-author Andrew Oswald, a professor of economics and behavioral science gathered informationfrom nearly 700,000 people, who were asked annually over a three-decade period how they felt on a numerical scale about their job, spouse, health and home. Using the data collected, researchers constructed statistical models to show how people felt and the actions they took as a result of their reported feelings. The study found that ratings of life satisfaction had a direct linear (线性的) relationship to actions people subsequently take. Participants who rated their job satisfaction as a 2 out of 7 had a 25% probability of quitting their job. Those who rated a 6 out of 7 had only a 10 percent probability of quitting. The same was true across other measures like marriage, health and housing.Previous research has also shown data about feelings predict human outcomes, but not in such a linear fashion; the degree of satisfaction served as a good predictor of future actions. Additionally, economists have previously been critical of feelings data because they considered them unscientific and unreliable. But this study shows socioeconomic factors have a lesser probability of predicting human behavior than data on feelings.Though the study shows numbers can quantify feelings, researchers are still a bit confused as to why estimates of seemingly subjective feelings can be such good predictors of future actions. According to Oswald, a number of factors could be at play. Humans are very experienced in comparative thinking and are able to scale their own life satisfaction against that of their neighbors. We’re also accustomed to using measuring devices for other aspects of life like temperature, distance and weight, so it shouldn’t be too surprising that we’re able to measure our feelings in a similarly accurate way. Another study co-author Caspar Kaiser says that it may also be because we communicate our feelings and do it in a scaled fashion every day. This could be why it comes out in the data more accurately than in objective markers.Ori Heffetz, an economics professor who was not involved in the study, says that this research shows feelings data shouldn’t be underestimated even if they’re more difficult to study. “Scientists who ignore this do so at their own risk,” he says.Looking ahead, Kaiser hopes this same data can be studied in lower-income countries so that it can be applied universally to places with varied levels of economic development. But more than anything else he’s interested in studying why feelings work so well.18．Paragraph 2 is mainly about .A．research process and findingsB．research topic and significanceC．research subjects and purposeD．research data collection and analysis19．What can we know about the study?A．It also applies to people from lower-income countries.B．It challenges the opinion that feelings data are unreliable.C．It explains why ratings of feelings can foresee future actions.D．It first shows data about feelings can predict human behavior20．What is Ori’s attitude towards the study?A．Neutral. B．Skeptical. C．Supportive. D．Cautious.21．Which would be the best title for the passage?A．How You Rate Your Life Predicts Your Future BehaviorB．Feelings Forecast Actions Better than Economic FactorsC．Why Your Feelings Affect Your Future ActionsD．Ranking Every Aspect of Your Life Counts（2023秋·北京西城·高三统考期末）Of the more than 3,000 species of mosquitoes in the world, just a small number specialize in sucking human blood. How mosquitoes track us down so effectively isn’t currently known, but it matters, since they carry dangerous diseases which may cause death.“In fact, stopping these annoying insects in their tracks could save up to half a million lives lost to those diseases each year,” said Carolyn Gauff, a professor of ecology and evolutionary biology at the Princeton Neuroscience Institute. That’s why Gauff’s team wants to understand how they find and target humans.Mosquitoes mostly choose what to bite based on odor (气味). Knowing how a potentially disease-carrying mosquito finds a person, while ignoring other warm-blooded animals, is a key question. But it’s not easy to answer, since any animal smell is made up of hundreds of chemicals mixed together in specific percentage. “The actual chemicals that are found in human odor are basically the same as the chemicals found in animal odor—it’s the percentages and the relative large amount of those substances in human mixtures that’s unique,” said Gauff.To investigate, researchers decided to record neural activity in the brain of mosquitoes while exposing them to natural human and animal odor samples. They collected odor samples from about 40 different animals. When they compared some of those with the 16 human samples, something jumped out. Decanal is particularly rich in human skin. Common in the natural world, in humans, decanal comes from another, more complex substance. When one component of our skin’s natural oils, sapienic acid, breaks down, decanal is left over. This acid is only found in human beings. It’s what likely leads to the high levels of decanal that help the mosquitoes smell their way to us.Understanding what the mosquitoes are targeting is only part of the story; knowing how they do it is also important. To see exactly how mosquitoes use this sense, scientists used genetically modified (转基因的) mosquitoes so that they could cut open mosquitoes’ heads and watch neurons firing when they’re exposed to human and animal odors. The research team already knew that mosquitoes have about 60 different types of neurons that sense odors, so when they looked in the insects’ brains, they thought they might see a lot of activity. But it was surprisingly quiet, meaning that the signal was perhaps quite simple, down to just a couple types of neurons. “One type of neuron responded really strongly to both humans and animals. Another type of neuron responded to both—but it responded much more strongly to humans than animals,” Gauff said.How to keep mosquitoes’ decanal signal from being transmitted will be the research team’s next focus. Gauff hoped their current work could be used to make mosquito killers and attractants to prevent disease. 22．What’s the final purpose of the research conducted by Gauff’s team?A．To study why only certain mosquitoes suck human blood.B．To investigate the neural activity in mosquitoes’ brains.C．To help prevent deadly diseases caused by mosquitoes.D．To test the effectiveness of mosquito killers.23．To which substance(s) would mosquitoes mostly be attracted?A．Natural oil from human skin.B．Chemicals in the environment.C．Decanal generated in human blood.D．Remains of decomposed sapienic acid.24．What can we learn from the passage?A．Most mosquito neurons are not involved in responding to human odor.B．Genetically modified mosquitoes are not sensitive to human odor.C．Further research will focus on odor signal and neural connection.D．Chemicals found in human and animal odors are quite different.（2023秋·北京东城·高三统考期末）Every robot is trained in some way to do a task. By seeing what to do, robots can copy the way of doing the task. But they do so unthinkingly, perhaps relying on sensors to try to reduce collision (碰撞) risks, rather than having any understanding of why they are performing the task or where they are within physical space. It means they will often make mistakes—hitting the object in their way, for instance.Hod Lipson and his colleagues are trying to face the challenge. They placed a robot arm in a laboratory where it was surrounded by four cameras at ground level and one camera above it. These fed video images back to a deep neural(神经的) network, a form of AI, connected to the robot that monitored its movement within the space. For 3 hours, the robot arm moved randomly and the neural network was fed information about the arm' s mechanical inputs and watched how it responded by seeing where it moved to in the space. This generated nearly 8,000 data points—and the team generated an additional 10,000 through a simulation (模拟) of the robot in a virtual version of its environment.To test how well the AI had worked, a cloud-like diagram was generated to show where the neural network “thought” the arm should be found as it moved. It was accurate to within 1 percent, meaning if the workspace was 1 metre wide, the system correctly estimated its position to within 1 centimetre. If the neural network is considered to be part of the robot itself, this suggests the robot has the ability to visualise where it physically is at any given moment.“To me, this is the first time in the history of robotics that a robot has been able to create a mental model of itself,” says Lipson. “It’s a small step, but it’s a sign of things to come.”Learning about the research, Andrew Hundt at the Georgia Institute of Technology says, “There is potential for further research to lead to useful applications based on this method, but not self- perception. The computer simply matches shape and motion patterns that happen to be in the shape of a robot arm that moves.” David Cameron at the University of Sheffield, UK, also says that following a specified path to complete a goal is easily achieved by existing robots.25．Hod Lipson’s work focuses on robots .A．flexibility B．self-awarenessC．deep-learning ability D．error correction26．What is the function of the neural network in the experiment?A．To process and transform neural information.B．To study and simulate AI’s virtual environment.C．To analyse and predict the arm’s position changes.D．To record and output the video images of the robot.27．As for the result of the experiment, Andrew Hundt is .A．sympathetic B．contentC．uncertain D．disapproving 28．What is the main purpose of the passage?A．To discuss a scientific concept.B．To assess a scientific finding.C．To introduce a science application.D．To present a science research.参考答案1．B 2．A 3．B【导语】本文是一篇说明文。
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Physiological Effects of CurrentsElectrical potential differences and currents play a vital role in the nervous systems of animals (Fig. T9.1). Conduction of nerve impulses is basically an electrical process, although the mechanism of conduction is much more complex than in simple materials such as metals. A nerve fiber, or axon, along which an electrical impulse can travel has a cylindrical membrane with one conducting fluid inside and another outside (Fig. T9.2a). In the resting condition the only charged bodies that can cross the membrane are positively charged potassium ions, which leak out of the axon into the surroundings. This leaves the inside of the axon with a net negative charge and a potential of about−70 mV (−0.07 V) with respect to the outer fluid.When an electrical stimulus is applied to the axon, the membrane temporarily becomes more permeable to other ions in the fluids, leading to a local change in potential difference (Fig. T9.2b). This disturbance, called the action potential,propagates along the membrane as a pulse with a speed of the order of 30 m/s. The entire pulse passes a given point along the axon in a few milliseconds, after which the membrane recovers and the potential difference returns to its initial value (Fig.T9.2c).The electrical nature of nerve impulses explains why the body is sensitive to externally supplied electrical currents. Currents through the body as small as 0.1A can be fatal because they interfere with essential nerve processes such as those in the heart. Even smaller currents can also be very dangerous. A current of 0.01A through an arm or leg causes strong, convulsive muscle action and considerable pain; with a current of 0.02 A, a person holding the conductor that is inflicting the shock is typically unable to release it. Currents of this magnitude through the chest can cause ventricular fibrillation, a disorganized twitching of heart muscles that pumps very little blood. Surprisingly, very large currents (over 0.1A) are somewhat less likely to cause fatal fibrillation because the heart muscle is“clamped”in one position. The heart actually stops beating and is more likely to resume normal beating when the current is removed. The electric defibrillators used for medical emergencies apply a large current pulse to stop the heart (and the fibrillation) to give the heart a chance to restore normal rhythm.Body fluids are usually quite good conductors because of their substantial ion concentrations. By comparison the resistance of skin is relatively high, ranging from 500 kΩfor very dry skin to 1000Ωor so for wet skin, depending also on the area of contact. If R=1000Ω, a current of 0.1 A requires a potential difference of V=IR=(0.1 A)(1000Ω)=100 V. Were it not for the high resistance of skin, even an ordinary 1.5-V flashlight battery could produce a hazardous shock.In summary, electric current poses three different kinds of hazards: Interference with the nervous system, injury caused by convulsive muscle action, and burns from I2R heating. The moral of this rather morbid story is that under certain conditions, voltages as small as 10V can be dangerous. All electrical circuits and electrical equipment should always be approached with respect and caution.On the positive side, alternating currents with frequencies of the order of 106Hz do not interfere appreciably with nerve processes and can be used for therapeutic heating for arthritic conditions, sinusitis, and other disorders. If one electrode is made very small, the resulting concentrated heating can be used for local destruction of tissue such as tumors or for cutting tissue in certainsurgical procedures.The study of particular nerve impulses is an important diagnostic tool in medicine. The most familiar examples are electrocardiography (EKG) and electroencephalography (EEG).Electrocardiograms, obtained by attaching electrodes to the chest and back and recording the regularly varying potential differences, are used to study heart function. Electrodes attached to the scalp permit study of potentials in the brain, and the resulting patterns can be helpful in diagnosing disorders such as epilepsy or brain tumors.Potassium ions (K+) play an essential role in nerve conduction. A healthy diet includes foods rich in potassium, such as bananas, tomatoes, spinach, and oranges.(a) The cell membrane around an axon maintains a resting potential difference of about−70mV between inner and outer fluids. (b) An electrical stimulus depolarizes the membrane, and the potential difference suddenly rises to about 30mV. (c) The change in potential difference,called the action potential, propagates along the axon. After the pulse passes, the potential difference first overshoots to about−90mV,then recovers its original value.。